Thermal processing apparatus and method of controlling the same

ABSTRACT

A control unit can select a large-number control zone model in which the number of control zones, which are independently controlled, is large, and a small-number control zone model in which the number of control zones, which are independently controlled, is small. When a temperature is increased or decreased, the control unit can select the small-number control zone model so as to control, based on signals from temperature sensors of the respective control zones C 1  . . . C 5  whose number is small, heaters located on the respective control zones C 1  . . . C 5 . When a temperature is stabilized, the control unit can select the large-number control zone model so as to control, based on signals from the temperature sensors of the respective control zones C 1  . . . C 10  whose number is large, the heaters located on the respective control zones C 1  . . . C 10 .

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2011-044197 filed on Mar. 1,2011, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermal processing apparatus and amethod of controlling the same.

2. Description of Related Art

In the manufacture of semiconductor devices, various thermal processingapparatuses are used for subjecting objects to be processed, such assemiconductor wafers, to thermal processes such as an oxidation process,a diffusion process, a CVD process and an annealing process. As one ofsuch processing apparatuses, there is known a vertical-type thermalprocessing apparatus capable of thermally processing a number of objectsto be processed at once. The vertical-type thermal processing apparatusincludes: a quartz processing vessel having a lower opening; a lidmember configured to open and close the opening of the processingvessel; a holder disposed on the lid member, the holder being configuredto hold a plurality of objects to be processed with equal intervalstherebetween in an up and down direction; and a furnace body disposedaround the processing vessel, and provided with a heater for heating theobjects to be processed loaded into the processing vessel.

In order to precisely control a temperature in the furnace body, thefollowing conventional technique has been developed. Namely, a space inthe furnace body is divided into a plurality of control zones, andin-furnace temperature sensors are placed in the respective controlzones. In addition, a heater is divided for the respective controlzones, whereby temperatures of the respective control zones are finelycontrolled.

However, when the inside space of the furnace body is divided into theplurality of control zones, and the respective control zones are finelycontrolled, a problem occurs in that it is difficult to control atemperature when it is increased or decreased so that it takes a lot oftime to tune control parameters, although a temperature uniformity canbe improved when the temperature is stabilized.

-   Patent Document 1: JP2002-305189A-   Patent Document 2: JP2005-188869A

The present invention has been made in view of the above circumstances.The object of the present invention is to provide a thermal processingapparatus and a method of controlling the same, which are capable ofimproving a temperature uniformity in a furnace body when a temperatureis stabilized, and of easily controlling the temperature in the furnacebody when a temperature is increased or decreased.

SUMMARY OF THE INVENTION

A thermal processing apparatus in one embodiment is a thermal processingapparatus comprising: a furnace body; a processing vessel disposed inthe furnace body, the processing vessel defining, between the furnacebody and the processing vessel, a space including therein a plurality ofunit areas, and the processing vessel being configured to accommodate aplurality of objects to be processed; a heating unit disposed on aninner surface of the furnace body, correspondingly to each of the unitareas of the space; an in-furnace temperature sensor disposedcorrespondingly to each of the unit areas of the space; and a controlunit configured to control, based on a signal from the in-furnacetemperature sensor of each of the unit areas, the heating unit of theunit area; wherein: the control unit includes a large-number controlzone mode in which the number of control zones, which are formed of theunit areas and are independently controlled, is large, and asmall-number control zone mode in which the number of control zones,which are formed of the unit areas and are independently controlled, issmall; and the control unit is configured to select the small-numbercontrol zone mode in which the number of the control zones is small, soas to control the heating units of the respective control zones, when atemperature is increased or decreased, and is configured to select thelarge-number control zone mode in which the number of the control zonesis large, so as to control the heating units of the respective controlzones, when a temperature is stabilized.

In the thermal processing apparatus, in the large-number control zonemode, each of the control zones is formed of the one unit area, and thecontrol unit is configured to control, based on a signal from thein-furnace temperature sensor of the one unit area, the heating unit ofthe unit area; and in the small-number control zone mode, at least theone control zone is formed of the plurality of adjacent unit areas, andthe control unit is configured to control, based on a signal from thein-furnace temperature sensor of the desired unit area out of theplurality of the unit areas, the heating units of the plurality of unitareas.

In the thermal processing apparatus, the control unit is configured tocontrol, in the large-number control zone mode, the heating unit in eachof the control zones based on a previously incorporated numerical modelfor large-number control zones, and is configured to control, in thesmall-number control zone mode, the heating unit in each of the controlzones based on a previously incorporated numerical model forsmall-number control zones.

In the thermal processing apparatus, a blower is connected to thefurnace body through a cooling-medium supply line, the blower beingconfigured to supply a cooling medium to the space between the furnacebody and the processing vessel, and the furnace body is provided with anexhaust pipe; and the control unit is configured to control, based on asignal from the in-furnace temperature sensor of each of the unit areas,the heating unit of the unit area and the blower.

In the thermal processing apparatus, the control unit is configured toselect the small-number control zone mode so as to control the heatingunit of each of the control zones and the blower, when a temperature isincreased or decreased.

A thermal processing apparatus in another embodiment is a thermalprocessing apparatus comprising: a furnace body: a processing vesseldisposed in the furnace body, the processing vessel defining, betweenthe furnace body and the processing vessel, a space including therein aplurality of unit areas, and the processing vessel being configured toaccommodate a plurality of objects to be processed; a heating unitdisposed on an inner surface of the furnace body, correspondingly toeach of the unit areas of the space; an in-processing-vessel temperaturesensor disposed correspondingly to each of the unit areas in theprocessing vessel; and a control unit configured to control, based on asignal from the in-processing-vessel temperature sensor of each of theunit areas, the heating unit of the unit area; wherein: the control unitincludes a large-number control zone mode in which the number of controlzones, which are formed of the unit areas and are independentlycontrolled, is large, and a small-number control zone mode in which thenumber of control zones, is small; and the control unit is configured toselect the small-number control zone mode in which the number of thecontrol zones is small, so as to control the heating units of therespective control zones, when a temperature is increased or decreased,and is configured to select the large-number control zone mode in whichthe number of the control zones is large, so as to control the heatingunits of the respective control zones, when a temperature is stabilized.

In the thermal processing apparatus, in the large-number control zonemode, each of the control zones is formed of the one unit area, and thecontrol unit is configured to control, based on a signal from thein-processing-vessel temperature sensor of the one unit area, theheating unit of the unit area; and in the small-number control zonemode, at least the one control zone is formed of the plurality of theadjacent unit areas, and the control unit is configured to control,based on a signal from the in-processing-vessel temperature sensor ofthe desired unit area out of the plurality of the unit areas, theheating units of the plurality of unit areas.

In the thermal processing apparatus, the control unit is configured tocontrol, in the large-number control zone mode, the heating unit in eachof the control zones based on a previously incorporated numerical modelfor large-number control zones, and is configured to control, in thesmall-number control zone mode, the heating unit in each of the controlzones based on a previously incorporated numerical model forsmall-number control zones.

In the thermal processing apparatus, a blower is connected to thefurnace body through a cooling-medium supply line, the blower beingconfigured to supply a cooling medium to the space between the furnacebody and the processing vessel, and the furnace body is provided with anexhaust pipe; and the control unit is configured to control, based on asignal from the in-processing-vessel temperature sensor of each of theunit areas, the heating unit of the unit area and the blower.

In the thermal processing apparatus, the control unit is configured toselect the small-number control zone mode so as to control the heatingunit of each of the control zones and the blower, when a temperature isincreased or decreased.

A method of controlling a thermal processing apparatus in one embodimentis a method of controlling a thermal processing apparatus comprising: afurnace body; a processing vessel disposed in the furnace body, theprocessing vessel defining, between the furnace body and the processingvessel, a space including therein a plurality of unit areas, and theprocessing vessel being configured to accommodate a plurality of objectsto be processed; a heating unit disposed on an inner surface of thefurnace body, correspondingly to each of the unit areas of the space; anin-furnace temperature sensors disposed correspondingly to each of theunit areas of the space; and a control unit configured to control, basedon a signal from the in-furnace temperature sensor of each of the unitareas, the heating unit of the unit area; wherein the control unitincludes a large-number control zone mode in which the number of controlzones, which are formed of the unit areas and are independentlycontrolled, is large, and a small-number control zone mode in which thenumber of control zones, which are formed of the unit areas and areindependently controlled, is small; the method of controlling thethermal processing apparatus comprising: selecting the small-numbercontrol zone mode in which the number of the control zones is small, soas to control the heating units of the respective control zones, when atemperature is increased or decreased; and selecting the large-numbercontrol zone mode in which the number of the control zones is large, soas to control the heating units of the respective control zones, when atemperature is stabilized.

In the method of controlling a thermal processing apparatus, in thelarge-number control zone mode, each of the control zones is formed ofthe one unit area, and the control unit is configured to control, basedon a signal from the in-furnace temperature sensor of the one unit area,the heating unit of the unit area; and in the small-number control zonemode, at least the one control zone is formed of the plurality ofadjacent unit areas, and the control unit is configured to control,based on a signal from the in-furnace temperature sensor of the desiredunit area out of the plurality of the unit areas, the heating units ofthe plurality of unit areas.

In the method of controlling a thermal processing apparatus, the controlunit is configured to control, in the large-number control zone mode,the heating unit in each of the control zones based on a previouslyincorporated numerical model for large-number control zones, and isconfigured to control, in the small-number control zone mode, theheating unit in each of the control zones based on a previouslyincorporated numerical model for small-number control zones.

In the method of controlling a thermal processing apparatus, a blower isconnected to the furnace body through a cooling-medium supply line, theblower being configured to supply a cooling medium to the space betweenthe furnace body and the processing vessel, and the furnace body isprovided with an exhaust pipe; and the control unit is configured tocontrol, based on a signal from the in-furnace temperature sensor ofeach of the unit areas, the heating unit of the unit area and theblower.

In the method of controlling a thermal processing apparatus, the controlunit is configured to select the small-number control zone mode so as tocontrol the heating unit of each of the control zones and the blower,when a temperature is increased or decreased.

A method of controlling a thermal processing apparatus in anotherembodiment is a method of controlling a thermal processing apparatuscomprising: a furnace body; a processing vessel disposed in the furnacebody, the processing vessel defining, between the furnace body and theprocessing vessel, a space including therein a plurality of unit areas,and the processing vessel being configured to accommodate a plurality ofobjects to be processed; a heating unit disposed on an inner surface ofthe furnace body, correspondingly to each of the unit areas of thespace; an in-processing-vessel temperature sensor disposedcorrespondingly to each of the unit areas in the processing vessel; anda control unit configured to control, based on a signal from thein-processing-vessel temperature sensor of each of the unit areas, theheating unit of the unit area; wherein the control unit includes alarge-number control zone mode in which the number of control zones,which are formed of the unit areas and are independently controlled, islarge, and a small-number control zone mode in which the number ofcontrol zones, which are formed of the unit areas and are independentlycontrolled, is small; the method of controlling the thermal processingapparatus comprising: selecting the small-number control zone mode inwhich the number of the control zones is small, so as to control theheating units of the respective control zones, when a temperature isincreased or decreased; and selecting the large-number control zone modein which the number of the control zones is large, so as to control theheating units of the respective control zones, when a temperature isstabilized.

In the method of controlling a thermal processing apparatus, in thelarge-number control zone mode, each of the control zones is formed ofthe one unit area, and the control unit is configured to control, basedon a signal from the in-processing-vessel temperature sensor of the oneunit area, the heating unit of the unit area; and in the small-numbercontrol zone mode, at least the one control zone is formed of theplurality of adjacent unit areas, and the control unit is configured tocontrol, based on a signal from the in-processing-vessel temperaturesensor of the desired unit area out of the plurality of the unit areas,the heating units of the plurality of unit areas.

In the method of controlling a thermal processing apparatus, the controlunit is configured to control, in the large-number control zone mode,the heating unit in each of the control zones based on a previouslyincorporated numerical model for large-number control zones, and isconfigured to control, in the small-number control zone mode, theheating unit in each of the control zones based on a previouslyincorporated numerical model for small-number control zones.

In the method of controlling a thermal processing apparatus, a blower isconnected to the furnace body through a cooling-medium supply line, theblower being configured to supply a cooling medium to the space betweenthe furnace body and the processing vessel, and the furnace body isprovided with an exhaust pipe; and the control unit is configured tocontrol, based on a signal from the in-processing-vessel temperaturesensor of each of the unit areas, the heating unit of the unit area andthe blower.

In the method of controlling a thermal processing apparatus, the controlunit is configured to select the small-number control zone mode so as tocontrol the heating unit of each of the control zones and the blower,when a temperature is increased or decreased.

According to the present invention, since the small-number control zonemode in which the number of the control zones is small, is selected soas to control the heaters of the respective control zones, when thetemperature is increased or decreased, the control of a temperature inthe furnace body can be facilitated. In addition, since the large-numbercontrol zone mode in which the number of the control zones is large, isselected so as to control the heaters of the respective control zones, auniformity in temperature in the furnace body can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view schematically showing anembodiment of a thermal processing apparatus and a method of controllingthe same of the present invention.

FIG. 2 is a schematic view showing a control unit of the thermalprocessing apparatus.

FIG. 3( a) is a view showing a small-number control zone model control,and FIG. 3( b) is a view showing a large-number control zone modelcontrol.

FIG. 4 is a view showing a temperature change in a furnace body overtime.

FIG. 5 is a schematic view showing temperatures in respective unit areasof the furnace body.

FIG. 6 is a view schematically showing an alternative example of thethermal processing apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment of the Invention

An embodiment of the present invention will be described herebelow withreference to the drawings.

In FIG. 1, a vertical-type thermal processing apparatus 1 includes avertical-type thermal processing furnace 2 capable of simultaneouslyaccommodating a number of objects to be processed, e.g., semiconductorwafers w, and of subjecting the semiconductor wafers w to variousthermal processes such as an oxidation process, a diffusion process, alow-pressure CVD process and so on. The thermal processing furnace 2includes a furnace body 5 and a processing vessel 3 disposed in thefurnace body 5 so as to define a space 33 between the processing vessel3 and the furnace body 5. A plurality of heating resistors (heaters) 18Aserving as a heating unit are disposed on an inner circumferentialsurface of the thermal processing furnace 2. The processing vessel 3 isconfigured to accommodate and thermally process wafers w.

The space 33 between the furnace body 5 and the processing vessel 3 isdivided into a plurality of unit areas (also referred to simply as“area”), e.g., ten unit areas A₁, A₂, A₃, A₄, A₅, A₆, A₇, A₈, A₉ andA₁₀, along a longitudinal direction. Each heater 18A is disposedcorrespondingly to one of the ten unit areas A₁ . . . A₁₀. In addition,as described below, a plurality of in-furnace temperature sensors 50 formeasuring temperatures of the respective unit areas A₁ . . . A₁₀ aredisposed in the unit areas A₁ . . . A₁₀, respectively. The respectivein-furnace temperature sensors 50 are connected to a control unit 51,which is described below, through a signal line 50 a.

Similarly, an inside of the processing vessel 3 is divided into aplurality of unit areas (also referred to simply as “area”), e.g., tenunit areas A₁, A₂, A₃, A₄, A₅, A₆, A₇, A₈, A₉ and A₁₀ in accordance withthe unit areas of the space 33 along the longitudinal direction.In-processing-vessel temperature sensors 55 for measuring temperaturesof the respective unit areas A₁ . . . A₁₀ are disposed correspondinglyto the respective unit areas A₁ . . . A₁₀. The respectivein-processing-vessel temperature sensors 55 are supported byin-processing-vessel temperature sensor supporters 56, and are connectedto the control unit 51 through a signal line 55 a.

The furnace body 5 is supported by a base plate 6. The base plate 6 hasan opening 7 through which the processing vessel 3 is inserted upwardfrom below. A not-shown heat insulation member is disposed on theopening 7 of the base plate 6, such that a gap between the base plate 6and the processing vessel 3 is covered.

The processing vessel 3 is made of quartz, and has an elongatedcylindrical shape with a closed upper end and an opened lower endserving as a furnace opening 3 a. An outward flange 3 b is formed on thelower end of the processing vessel 3. The flange 3 b is supported by thebase plate 6 through a not-shown flange presser. In addition, theprocessing vessel 3 is provided with, on a lower side thereof, an inletport (inlet opening) 8 through which a process gas and an inert gas areintroduced into the processing vessel 3, and a not-shown exhaust port(exhaust opening) through which a gas in the processing vessel 3 isdischarged. A gas supply source (not shown) is connected to the inletport 8. Connected to the exhaust port is an exhaust system (not shown)including a vacuum pump that can control and decompress a pressure toabout 133×600 Pa to 133×10⁻² Pa, for example. A gas supply pipe 8 aextending into the processing vessel 3 is connected to the inlet port 8.Gas supply holes 8 b are formed in the gas supply pipe 8 a.

A lid member 10 for closing the furnace opening 3 a of the processingvessel 3 is disposed below the processing vessel 3, such that the lidmember 10 can be elevated and lowered by a not-shown elevatingmechanism. A heat retention tube 11, which is a heat retention means ofthe furnace opening, is placed on an upper part of the lid member 10. Onan upper part of the heat retention tube 11, there is placed a quartzboat 12 which is a holder for holding a number of 300-mm diameter wafersw, e.g., about one hundred to one hundred and fifty wafers w, withpredetermined intervals therebetween in the up and down direction. Thelid member 10 is equipped with a rotation mechanism 13 configured torotate the boat 12 about its center axis. The boat 12 is unloaded fromthe inside of the processing vessel 3 into a below loading area (notshown) by a downward movement of the lid member 10. After wafers w havebeen replaced, the boat 12 is loaded into the processing vessel 3 by anupward movement of the lid member 10.

The furnace body 5 includes a cylindrical heat insulation member 16, anda plurality of groove-shaped shelf parts 17 which are formed in an innercircumferential surface of the heat insulation member 16 in an axialdirection thereof (in the up and down direction in the illustratedexample) at multiple stages. Heater elements (heating wires, heatingresistors) 18, which constitute the heaters 18A disposed on therespective unit areas A₁ . . . A₁₀, are positioned along the respectiveshelf parts 17. The heat insulation member 16 is formed of inorganicfibers including silica, alumina or alumina silicate, for example.

A plurality of annular groove parts 21, which are coaxial with the heatinsulation member 16, are formed in the inner circumferential surface ofthe cylindrical heat insulation member 16 in the axial direction withpredetermined pitches at multiple stages. The circumferentiallycontinuous annular shelf parts 17 are formed between each upper groovepart 21 and each lower groove part 21 adjacent thereto. Gaps, which aresufficient for allowing a thermal expansion and contract of each heaterelement 18 and a radial movement thereof, are defined in an upper partand a lower part of the heater element 18 in the groove part 21, and ina space between a rear wall of the groove part 21 and the heater element18. Due to these gaps, a cooling medium flowing from a cooling-mediumintroduction unit 40 of the furnace body 5 into the space 33 can goaround a rear side of each heater element 18, so that the heater element18 can be effectively cooled upon a forcible cooling operation. Air andnitrogen gas may be supposed as such a cooling medium. The coolingmedium is sent to the cooling-medium introduction unit 40 by acooling-medium supply blower (not shown) driven by an inverter outputunit 53 a which is described below.

In the heater 18A disposed on each of the unit areas A₁ . . . A₁₀,terminal plates 22 a and 22 b are joined to the heater elements 18constituting the heater 18A. Each of the heaters 18A is connected to anoutside heater output unit 18B through the terminal plates 22 a and 22 bwhich are disposed to radially pass through the heat insulation member16.

In order to hold the shape of the heat insulation member 16 of thefurnace body 5 and to reinforce the heat insulation member 16, as shownin FIG. 1, an outer circumferential surface of the heat insulationmember 16 is covered with an outer shell 30 made of metal, e.g.,stainless. An upper heat insulation member 31 is disposed on a top partof the heat insulation member 16 so as to cover the same. A stainlesstop plate 32 covering a top part (upper end part) of the outer shell 30is disposed on an upper part of the upper heat insulation member 31.

In the above example, a strip-like heating resistor is used as theheater element 18 and the heater element 18 is accommodated in the shelfpart 17. However, not limited to this structure, a heater element ofanother structure may be used as the heater element 18.

As described above, the space 33 defined between the furnace body 5 andthe processing vessel 3 is divided into the ten unit areas A₁ . . . A₁₀.The temperature sensors (in-furnace temperature sensors) 50 fordetecting temperatures of the respective unit areas A₁ . . . A₁₀ arelocated on the unit areas A₁ . . . A₁₀, respectively. Detection signalsfrom the respective temperature sensors 50 are transmitted to thebelow-described control unit 51 through the signal line 50 a.

The temperature sensors 50 located on the respective unit areas A₁ . . .A₁₀ are connected to the control unit 51. The control unit 51 isdescribed in detail below.

As described above, the temperature sensors 50 are located on therespective unit areas A₁ . . . A₁₀ of the space 33 so as to detecttemperatures of the respective unit areas A₁ . . . A₁₀.

Detection signals detected by the temperature sensors 50 of therespective unit areas A₁ . . . A₁₀ are transmitted to the control unit51 through the signal line 50 a. The control unit 51 is configured toreduce a time period required for an actual temperature to be convergedto a predetermined target temperature, and to precisely make thetemperature close to the target temperature, in a temperature increaseprocess and a temperature decrease process of a lower temperature rangesuch as 100° C. to 500° C., and in a temperature stabilized period (FIG.2).

Namely, as shown in FIGS. 3( a) and 3(b), the control unit 51 has alarge-number control zone mode 72 a in which the number of the controlzones C₁, C₂, C₃, C₄, C₅, C₆, C₇, C₈, C₉ and C₁₀, which areindependently controlled, is large, and a small-number control zone mode72 b in which the number of control zones C₁, C₂, C₃, C₄ and C₅, whichare independently controlled, is small. The control unit 51 can selectany one of the large-number control zone mode 72 a and the small-numbercontrol zone mode 72 b.

When the control unit 51 selects the large-number control zone mode 72a, the control zones C₁ . . . C₁₀ to be independently controlledrespectively correspond to the ten unit areas A₁ . . . A₁₀ constitutingthe space 33 between the furnace body 5 and the processing vessel 3. Thecontrol unit 51 independently controls the control zones C₁ . . . C₁₀corresponding to the unit areas A₁ . . . A₁₀, respectively.

When the control unit 51 selects the small-number control zone mode 72b, the control zone C₁ to be independently controlled corresponds to theadjacent unit areas A₁ and A₂, the control zone C₂ corresponds to theadjacent unit areas A₃ and A₄, the control zone C₃ corresponds to theadjacent unit areas A₅ and A₆, the control zone C₄ corresponds to theadjacent unit areas A₇ and A₈, and the control zone C₅ corresponds tothe adjacent unit areas A₉ and A₁₀. The control unit 51 controls thecontrol zones C₁ to C₅ independently. When the small-number control zonemode 72 b is selected, a least one control zone may be composed of aplurality of unit areas adjacent to each other, and other control zonesmay be composed of the respective unit areas.

To be specific, when the control unit 51 selects the large-numbercontrol zone mode 72 a, based on signals from all the temperaturesensors 50 of the respective unit areas A₁ . . . A₁₀, the control unit51 controls the heaters 18A of the corresponding unit areas A₁ . . .A₁₀, independently. In this case, the control unit 51 may control theheaters 18A of the respective unit areas A₁ . . . A₁₀, in considerationof a signal from an exhaust-air temperature sensor 80 disposed on anoutlet side of the space 33.

When the control unit 51 selects the small-number control zone mode 72b, the control unit 51 controls the heaters 18A, based on signals fromthe temperature sensors of every other unit area A₁, A₃, A₅, A₇ and A₉,for example. Specifically, the control unit 51 collectively controls theheaters 18A of the unit areas A₁ and A₂, based on a signal from thetemperature sensor 50 of the unit area A₁. The control unit 51collectively controls the heaters 18A of the unit areas A₃ and A₄, basedon a signal from the temperature sensor 50 of the unit area A₃. Thecontrol unit 51 collectively controls the heaters 18A of the unit areasA₅ and A₆, based on a signal from the temperature sensor 50 of the unitarea A₅. The control unit 51 collectively controls the heaters 18A ofthe unit areas A₇ and A₈, based on a signal from the temperature sensor50 of the unit area A₇. The control unit 51 collectively controls theheaters 18A of the unit areas A₉ and A₁₀, based on a signal from thetemperature sensor 50 of the unit area A₉. In this case, the controlunit 51 may control the heaters 18A of the respective unit areas A₁ . .. A₁₀, in consideration of a signal from the temperature sensor 80.

In addition, the control unit 51 includes: a predetermined numericalmodel 71 which relates to a heater output and a blower output; aheater-output calculation unit 51 a which calculates a heater outputbased on the numerical model 71 and an in-furnace temperature from thetemperature sensor 50; and a blower-output calculation unit 51 b whichcalculates a blower output based on the numerical model 71 and anin-furnace temperature from the temperature sensor 50.

The numerical model 71 includes: a numerical model 71 a for large-numbercontrol zones, which is used when the large-number control zone mode 72a is selected; a numerical model 71 b for small-number control zones,which is used when the small-number control zone mode 72 b is selected;and a numerical model 73 for blower output.

The heater-output calculation unit 51 a calculates outputs of theheaters 18A of the respective unit areas A₁ . . . A₁₀, based on eitherone of the numerical model 71 a for large-number control zones and thenumerical model 71 b for small-number control zones, and signals fromthe temperature sensors 50 of the respective unit areas A₁ . . . A₁₀.Then, the heaters 18A of the unit areas A₁ . . . A₁₀ are controlled bythe heater output unit 18B, based on the outputs of the heaters 18Acalculated by the heater-output calculation unit 51 a. For example, whenthe control unit 51 selects the large-number control zone mode 72 a,outputs of the heaters 18A of all the unit areas A₁ . . . A₁₀ arecalculated by the heater-output calculation unit 51 a, based on thenumerical model 71 a for large-number control zones and signals from thetemperature sensors 50 of all the unit areas A₁ . . . A₁₀. Based on theoutputs of the heaters 18A, the heater output unit 18B drives andcontrols the heaters 18A of all the unit areas A₁ . . . A₁₀,independently.

The blower-output calculation unit 51 b calculates a blower output,based on the numerical model 73 for blower output and a signal from thetemperature sensor 50 of one of the unit areas A₁ . . . A₁₀. Based onthe blower output, an inverter output unit 53 a is controlled.

Among the models of the numerical model 71, the numerical model 71 a forlarge-number control zones for controlling the heaters is described.

The numerical model 71 a for large-number control zones is amathematical model which can previously estimate temperatures ofsemiconductor wafers w from the temperature sensors 50 and the heateroutput unit 18B, and then specify a power to be supplied to the heater18 in order that the estimated temperatures are made close to a targettemperature as a whole. A given model (multi-variables,multi-dimensions, multi-output functions) can be utilized as thenumerical model 71 a for large-number control zones. As such a numericalmodel 71 a for large number control zones, a model disclosed in U.S.Pat. No. 5,517,594B can be used, for example.

In this manner, there can be obtained the numerical model 71 a forlarge-number control zones that can estimate a temperature of a wafer,and define an output for allowing the wafer temperature to be a targettemperature, depending on the number of wafers to be processed and anarrangement thereof. In the above example, although an estimated wafertemperature is to be controlled, the model may control an observedtemperature itself. The numerical model 71 b for small-number controlzones can be obtained in the same manner as the numerical model 71 a forlarge-number control zones. In this case, the numerical model 71 a forlarge-number control zones has a relationship between a time and atemperature respectively set for each control zone, when thelarge-number control zone mode 72 a is selected. The numerical model 71b for small-number control zones has a relationship between a time and atemperature respectively set for each control zone, when thesmall-number control zone mode 72 b is selected.

Similarly to the manner for obtaining the numerical model 71 a forlarge-number control zones and the numerical model 71 b for small-numbercontrol zones, the numerical model 73 for blower output can be obtained,by actually measuring a temperature of a semiconductor wafer w, whileactually operating a cooling-medium supply blower and operating theheater 18A.

In the above example, although the numerical model 71 includes in aseparate manner the numerical model 71 a for large-number control zones,the numerical model 71 b for small-number control zones and thenumerical model 73 for blower output, the single numerical model 71 mayinclude in a combined manner a numerical model for large-number controlzones, a numerical model for small-number control zones and a numericalmodel for blower output.

The heater outputs calculated by the heater-output calculation unit 51 aare transmitted to the heater output unit 18B. The heater elements 18 ofthe heaters 18A in the respective unit areas A₁ . . . A₁₀ are driven andcontrolled by the heater output unit 18B, based on the heater outputscalculated by the heater-output calculation unit 51 a.

On the other hand, the blower output calculated by the blower-outputcalculation unit 51 b is transmitted to the inverter output unit 53 a,and the cooling-medium supply blower is driven and controlled by theinverter output unit 53 a.

In this manner, a cooling medium is supplied by the cooling-mediumsupply blower into the space 33 between the furnace body 5 and theprocessing vessel 3.

Next, an operation of the thermal processing apparatus as structuredabove is described.

At first, wafers w are placed in the boat 12, and the boat 12 with thewafers w is put on the heat insulation tube 11 of the lid member 10.Then, the boat 12 is loaded into the processing vessel 3 by the upwardmovement of the lid member 10.

Then, the control unit 51 controls the heater output unit 18B so as tocontrol outputs of the heaters 18A in the respective unit areas A₁ . . .A₁₀. Thus, the space 33 between the furnace body 5 and the processingvessel 3 is heated, whereby the wafers w on the boat 12 in theprocessing vessel 3 are subjected to a required thermal process.

To be specific, when a temperature is increased or decreased, thecontrol unit 51 selects the small-number control zone mode 72 b in whichthe number of the control zones is small. In this case, the inside ofthe space 33 between the furnace body 5 and the processing vessel 3 isdivided into the five control zones, C₁ . . . C₅, for example. Thecontrol zone C₁ corresponds to the unit areas A₁ and A₂, the controlzone C₂ corresponds to the unit areas A₃ and A₄, the control zone C₃corresponds to the unit areas A₅ and A₆, the control zone C₄ correspondsto the unit areas A₇ and A₈, and the control zone C₅ corresponds to theunit areas A₉ and A₁₀ (FIG. 3( a)).

At this time, the control unit 51 uses the numerical model 71 b forsmall-number control zones. Based on the numerical model forsmall-number control zones and signals from the temperature sensors 50of every other unit areas A₁, A₃, A₅, A₇ and A₉, the heater-outputcalculation unit 51 a calculates outputs of the heaters 18A of thecorresponding unit areas A₁ and A₂ (control zone C₁), outputs of theheaters 18A of the corresponding unit areas A₃ and A₄ (control zone C₂),outputs of the heaters 18A of the corresponding unit areas A₅ and A₆(control zone C₃), outputs of the heaters 18A of the corresponding unitareas A₇ and A₈ (control zone C₄), and outputs of the heaters 18A of thecorresponding unit areas A₉ and A₁₀ (control zone C₅).

Then, based on the heater outputs calculated by the heater-outputcalculation unit 51 a, the heater output unit 18B collectively controlsthe heaters 18A of the unit areas A₁ and A₂ (control zone C₁),collectively controls the heaters 18A of the unit areas A₃ and A₄(control zone C₂), collectively controls the heaters 18A of the unitareas A₅ and A₆ (control zone C₃), collectively controls the heaters 18Aof the unit areas A₇ and A₈ (control zone C₄), and collectively controlsthe heaters 18A of the unit areas A₉ and A₁₀ (control zone C₅).

When the temperature is stabilized, the control unit 51 selects thelarge-number control zone mode 72 a in which the number of the controlzones is large. In this case, the control zones C₁, C₂, C₃, C₄ . . . C₁₀respectively correspond to the unit areas A₁, A₂, A₃, A₄ . . . A₁₀ (FIG.3( b)).

At this time, the control unit 51 uses the numerical model 71 a forlarge-number control zones. Based on the numerical model 71 a forlarge-number control zones and signals from the temperature sensors 50of the respective unit areas A₁ . . . A₁₀, the heater-output calculationunit 51 a calculates outputs of the heaters 18A of the respective unitareas A₁ . . . A₁₀.

Then, the heater output unit 18B drives and controls the heaters 18A ofthe respective unit areas A₁ . . . A₁₀, independently, based on theheater outputs calculated by the heater output calculation unit 51 a.

As shown in FIG. 4, since the control unit 51 selects, in a temperatureincrease/decrease time T₁, the small-number control zone mode 71 b, andselects in a temperature stabilized time T₂, the large-number controlzone mode 71 a, so as to control the heaters 18A of the unit areas A₁ .. . A₁₀, the number of the control zones is made smaller in thetemperature increase/decrease time T₁ whereby the control parameters canbe easily tuned. In addition, as shown in FIG. 5, in the temperaturestabilized time T₂, the unit areas A₁ . . . A₁₀ can be finely, uniformlycontrolled. In the small-number control zone mode during the time T₁,detection temperatures from the temperature sensors 50, which are to becontrolled, sufficiently follow the set temperature, but temperatures ofthe temperature sensors (illustrated as temperatures which are not to becontrolled), which are not to be controlled, somewhat deviate from theset temperature. In the subsequent large-number control zone mode duringthe time T₂, detection temperatures from all the temperature sensors 50can be controlled within a range of ±1° C. relative to the settemperature.

As described below, during this time, the inside of the space 33 betweenthe furnace body 5 and the processing vessel 3 is forcibly cooled, inorder to make effective a thermal processing operation according toneed.

In this case, the cooling-medium supply blower is activated by thecontrol unit 51. At this time, a cooling medium (20 to 30° C.) is blownout from the cooling-medium introduction unit 40 into the space 33between the furnace body 5 and the processing vessel 3, so that theinside of the space 33 is forcibly cooled.

In this case, the blower-output calculation unit 51 b determines ablower output, based on the numerical model 73 for blower output and anin-furnace temperature from the temperature sensor 50 located on any ofthe unit areas A₁ . . . A₁₀. Based on the blower output, the inverteroutput unit 53 a drives and controls the cooling-medium supply blower.

Alternative Example of Thermal Processing Apparatus of the PresentInvention

Next, an alternative example of the thermal processing apparatus of thepresent invention is described.

In the above embodiment, the thermal processing apparatus is controlledby the control unit 51, based on signals from the in-furnace temperaturesensors 50 located in the respective unit areas A₁ . . . A₁₀ of thespace 33 defined between the furnace body 5 and the processing vessel 3.However, not limited thereto, the thermal processing apparatus may becontrolled by a control unit 51, based on signals from thein-processing-vessel temperature sensors 55 located in the respectiveunit areas A₁ . . . A₁₀ in the processing vessel 3.

Namely, as described above, the inside of the processing vessel 3 isdivided into the ten unit areas A₁ . . . A₁₀ in accordance with the tenunit areas A₁ . . . A₁₀. The in-processing-vessel temperature sensors 55for detecting temperatures of the unit areas A₁ . . . A₁₀ are located inthe respective unit areas A₁ . . . A₁₀. Detection signals from thein-processing-vessel temperature sensors 55 are transmitted to thecontrol unit (control device) through the signal line 55 a. Thein-processing-vessel temperature sensors 55 located in the respectiveunit areas A₁ . . . A₁₀ are supported by the in-processing-vesseltemperature sensor supporters 56.

Next, an alternative example of the present invention is described withreference to FIG. 6. FIG. 6 is a view schematically showing analternative example of the thermal processing apparatus of the presentinvention.

Structures of the thermal processing apparatus shown in FIG. 6 aresubstantially the same with the structures of the thermal processingapparatus shown in FIGS. 1 to 5, only excluding the structure of theprocessing vessel 3.

Namely, in FIG. 1, the processing vessel 3 is formed of a single tube.However, not limited thereto, the processing vessel 3 may have a dualtube structure including an outer tube 3A and an inner tube 3Bpositioned in the outer tube 3A.

In the thermal processing apparatus shown in FIG. 6, the same parts asthe parts of the thermal processing apparatus shown in FIGS. 1 to 5 areshown by the same reference numbers, and detailed description thereof isomitted.

In the above embodiment, the space 33 between the furnace body 5 and theprocessing vessel 3 and the inside of the processing vessel 3 aredivided into the ten unit areas A₁ . . . A₁₀. However, not limitedthereto, the number of the divided unit areas may be three or more. Inthis case, when the number of the unit areas is larger, the effect ofthe present invention can be more improved.

In addition, the space 33 and the inside of the processing vessel 3 areuniformly divided. However, not limited thereto, depending on a usedcondition of the apparatus, a width, a position and a shape of the unitarea may be varied, which makes no difference in effect of the presentinvention.

The invention claimed is:
 1. A thermal processing apparatus comprising:a furnace body; a processing vessel disposed in the furnace body, theprocessing vessel defining a space between the furnace body and theprocessing vessel, the space including therein a plurality of unitareas, wherein the processing vessel is configured to accommodate aplurality of objects to be processed therein; a plurality of heatingunits disposed on an inner surface of the furnace body, corresponding toeach of the unit areas of the space; a plurality of in-furnacetemperature sensors disposed within the furnace and corresponding toeach of the unit areas of the space; and a control unit configured tocontrol the heating units of the unit areas, based on a signal from thein-furnace temperature sensors of each of the unit areas; wherein thecontrol unit includes a first control zone mode in which a number ofcontrol zones, which are formed of the unit areas and are independentlycontrolled, corresponds to a total number of the unit areas, and asecond control zone mode in which a number of control zones, which areformed of the unit areas and are independently controlled, is less thanthe total number of the unit areas; and wherein the control unit isconfigured to select the second control zone mode to control the heatingunits of the respective control zones when a temperature is increased ordecreased, and is configured to select the first control zone mode tocontrol the heating units of the respective control zones when atemperature is stabilized.
 2. The thermal processing apparatus accordingto claim 1, wherein: in the first control zone mode, each of the controlzones is formed of one unit area, and the control unit is configured tocontrol, based on a signal from the in-furnace temperature sensor ofeach unit area, the heating unit each unit area; and in the secondcontrol zone mode, at least one control zone is formed of the pluralityof adjacent unit areas, and the control unit is configured to control,based on a signal from the in-furnace temperature sensor of the desiredunit area out of the plurality of the unit areas, the heating units ofthe plurality of unit areas.
 3. The thermal processing apparatusaccording to claim 1, wherein the control unit is configured to control,in the first control zone mode, the heating unit in each of the controlzones based on a previously incorporated numerical model for the firstcontrol zones, and is configured to control, in the second control zonemode, the heating unit in each of the control zones based on apreviously incorporated numerical model for second control zones.
 4. Thethermal processing apparatus according to claim 1, wherein: a blower isconnected to the furnace body through a cooling-medium supply line, theblower being configured to supply a cooling medium to the space betweenthe furnace body and the processing vessel, wherein the furnace body isprovided with an exhaust pipe; and wherein the control unit isconfigured to control the heating unit of the unit area and the blower,based on a signal from the in-furnace temperature sensor of each of theunit areas.
 5. The thermal processing apparatus according to claim 4,wherein the control unit is configured to select the second control zonemode to control the heating unit of each of the control zones and theblower, when a temperature is increased or decreased.
 6. A thermalprocessing apparatus comprising: a furnace body: a processing vesseldisposed in the furnace body, the processing vessel defining a spacebetween the furnace body and the processing vessel, the space includingtherein a plurality of unit areas, wherein the processing vessel isconfigured to accommodate a plurality of objects to be processedtherein; a plurality of heating units disposed on an inner surface ofthe furnace body, corresponding to each of the unit areas of the space;a plurality of in-processing vessel temperature sensors disposed withinthe processing vessel and corresponding to each of the unit areas in theprocessing vessel; and a control unit configured to control the heatingunit of the unit area, based on a signal from the in-processing-vesseltemperature sensors of each of the unit areas; wherein the control unitincludes a first control zone mode in which the number of control zones,which are formed of the unit areas and are independently controlled,corresponds to a total number of the unit areas, and a second controlzone mode in which the number of control zones, less than the totalnumber of the unit areas; and wherein the control unit is configured toselect the second control zone mode to control the heating units of therespective control zones, when a temperature is increased or decreased,and is configured to select the first control zone mode to control theheating units of the respective control zones, when a temperature isstabilized.
 7. The thermal processing apparatus according to claim 6,wherein: in the first control zone mode, each of the control zones isformed of one unit area, and the control unit is configured to control,based on a signal from the in-processing-vessel temperature sensor ofeach unit area, the heating unit of each unit area; and in the secondcontrol zone mode, at least one control zone is formed of the pluralityof the adjacent unit areas, and the control unit is configured tocontrol, based on a signal from the in-processing-vessel temperaturesensor of the desired unit area out of the plurality of the unit areas,the heating units of the plurality of unit areas.
 8. The thermalprocessing apparatus according to claim 6, wherein the control unit isconfigured to control, in the first control zone mode, the heating unitin each of the control zones based on a previously incorporatednumerical model for the first control zones, and is configured tocontrol, in the second control zone mode, the heating unit in each ofthe control zones based on a previously incorporated numerical model forsecond control zones.
 9. The thermal processing apparatus according toclaim 6, wherein: a blower is connected to the furnace body through acooling-medium supply line, the blower being configured to supply acooling medium to the space between the furnace body and the processingvessel, and wherein the furnace body is provided with an exhaust pipe;and wherein the control unit is configured to control the heating unitof the unit area and the blower, based on a signal from thein-processing-vessel temperature sensor of each of the unit areas. 10.The thermal processing apparatus according to claim 9, wherein thecontrol unit is configured to select the second control zone mode tocontrol the heating unit of each of the control zones and the blower,when a temperature is increased or decreased.
 11. The thermal processingapparatus according to claim 1, wherein the plurality of heating unitsare disposed directly on the inner surface of the furnace body.
 12. Thethermal processing apparatus according to claim 6, wherein the pluralityof heating units are disposed directly on the inner surface of thefurnace body.